Abraham and Sarah were very old when God promised them a son. God had led them from their home and in trust they followed. God promised their descendents would be as numerous as the stars but they believed it to be impossible. As humans always do, they took the matter into their own hands and Abraham conceived a child with his slave girl Hagar, but this is not what God had in mind, he promised them a son and despite all the odds, the biological truths, the human limitations- Sarah gave birth in her old age, to a son.

When God makes a promise to us he keeps it, we do not need to find ingenious ways to take control of the situation, we just need to trust and follow his wishes.

Jesus rode into Jerusalem, with complete faith in what was about to happen.he knew he would be put to death and he knew he would rise again on the third day, it was God's will God's promise, and there was no doubt it would happen.

"The Lord blessed Sarah as he had promised, and she became pregnant and bore a son to Abraham when he was old." Genesis 21 vs 1-2